code: def test_HandleMissingIgnore(self):
      train = pd.DataFrame(
          {
              "x": ["A", "B", np.nan],
              "y": ["A", None, "A"],
              "z": [np.NaN, "B", "B"],
          }
      )
      train["z"] = train["z"].astype("category")
  
      expected_result = pd.DataFrame(
          {
              "x_A": [1, 0, 0],
              "x_B": [0, 1, 0],
              "y_A": [1, 0, 1],
              "z_B": [0, 1, 1],
          }
      )
      encoder = encoders.OneHotEncoder(
          handle_missing="ignore", use_cat_names=True
      )
      result = encoder.fit_transform(train)
  
      pd.testing.assert_frame_equal(result, expected_result)
  
imports: import pandas
  from unittest import TestCase
  import numpy
  import tests.helpers
  import category_encoders
label_desc: Use image node_id 12 for calling the TestOneHotEncoderTestCase obj's underlying member method code with example usage: obj.test_HandleMissingIgnore() without return types